Isolation and characterization of progenitor mesenchymal cells in human pituitary tumors.

The Cancer Stem Cells (CSCs) theory suggests that genetic alterations in stem cells are the direct cause for cancer. The evidence for a CSC population that results in pituitary tumors is poor. Some studies report the isolation of CSCs, but a deep characterization of the stemness of these cells is lacking. Here, we report the isolation and detailed characterization of progenitor mesenchymal cells (PMCs) from both growth hormone-secreting (GH(+)) and non-secreting (NS) pituitary adenomas, determining the immunophenotype, the expression of genes related to stemness or to pituitary hormone cell types, and the differentiative potential towards osteo-, chondro- and adipogenic lineages. Finally, the expression of CD133, known as a marker for CSCs in other tumors, was analyzed. Isolated cells, both from GH(+) and NS tumors, satisfy all the criteria for the identification of PMCs and express known stem cell markers (OCT4, SOX2, KLF4, NANOG), but do not express markers of pituitary hormone cell types (PITX2, PROP1, PIT1). Finally, PMCs express CD133. We demonstrated that pituitary tumors contain a stem cell population that can generate cell types characteristic of mesenchymal stem cells, and express CD133, which is associated with CSCs in other tumors.

Bone complications in patients with Cushing's syndrome: looking for clinical, biochemical, and genetic determinants.

SUMMARY: This is the first study examining the impact of both clinical, biochemical, and genetic determinants in the occurrence of bone complications in patients with overt Cushing's syndrome (CS). It demonstrates that the degree and duration of hypercortisolism seem to play a major role in bone loss and fractures development in these patients. INTRODUCTION: Bone loss and fractures are a common complication of CS. We investigate the role of gender, disease etiology, duration, and degree of hypercortisolism as well as the impact of glucocorticoid receptor (GR) polymorphisms on the development of bone complications in CS. METHODS: Fifty-two patients with active CS (38 Cushing's disease and 14 with cortisol-secreting adrenal adenoma) were genotyped for GR polymorphisms (BclI, N363S, ER22/23EK, and A3669G). In all patients, clinical, hormonal, and biochemical markers of bone turnover, densitometric parameters [lumbar spine and left femur bone mineral density (BMD), T-score, Z-score] as well as the prevalence of bone demineralization and both vertebral and peripheral fractures were assessed. RESULTS: No differences were found in bone complications according to gender, disease etiology, and genetic variants distribution. Fractured patients compared to non-fractured ones showed increased levels of urinary free cortisol (UFC) and a more compromised densitometric profile. UFC levels correlated with the occurrence of vertebral fractures (r = 0.43, p = 0.009) while midnight serum cortisol correlated with L1-L4 BMD values (r = -0.35, p = 0.04). Disease duration correlated with the presence of peripheral fractures (r = 0.36, p = 0.04). CONCLUSIONS: While GR gene variants as well as gender and disease etiology seem not to play a role, the degree and duration of hypercortisolism seem to be the major determinants of bone loss and fractures in this group of patients. More investigations are needed to understand the real impact of these determinants on the development of bone complications in patients with hypercortisolism.

Cyclical Cushing's syndrome in a patient with a bronchial neuroendocrine tumor (typical carcinoid) expressing ghrelin and growth hormone secretagogue receptors.

A 56-yr-old woman was referred with a diagnosis of Cushing's disease. Hypertension and severe hypokalemia were present and high urinary free cortisol/cortisone ratio was detected, raising a suspicion of an ectopic ACTH syndrome. Inferior petrosal sinus sampling, thoracic computed tomography, and octreotide scans were negative. Remission and relapse periods lasting 3-4 months were observed during the 3.5 yr of follow-up. Finally a thoracic computed tomography scan showed a basal paracardic nodule in the left lung. After surgery, a well-differentiated neuroendocrine tumor (typical bronchial carcinoid) was diagnosed, staining positively for ACTH. RT-PCR revealed expression of proopiomelanocortin, CRH receptor, and V3 vasopressin receptor. Somatostatin receptor type 1, 2, 3, and 5 mRNA was detected only in tumoral tissue. Interestingly, we observed the simultaneous presence of ghrelin and both GH secretagogue (GHS) receptors (1a and 1b) mRNA in tumoral tissue but not in the normal lung. This finding correlates with the in vivo ACTH hyperresponsiveness to hexarelin (a GHS). This is the first report of a cyclical ectopic ACTH-secreting tumor with an in vivo ACTH response to hexarelin coupled with the tumoral expression of ghrelin and GHS receptors. This finding might imply an autocrine/paracrine modulatory effect of ghrelin in bronchial ACTH-secreting tumors.